(a) Field of the Invention
The present invention relates to an illumination device, and more particularly to an illumination device using a light emitting diode as a light source and improving the illumination angle of the light source.
(b) Description of the Related Art
As the power saving issue becomes increasingly popular and governments of different countries prohibit the use of fluorescent bulbs. Light emitting diode (LED) has the advantages of high efficiency, power saving, and dimmerability, LED lamps become a trend in the illumination market, and used extensively in many fields such as road lamps, automobile lamps, outdoor illuminations and mood lighting.
However, the light emitting diode also has disadvantages, such as a small light emitting angle of tens of several degrees only. In other words, the light emitting diode has a high directivity, which is a negative number with respect to the wide-angle requirement of the illuminator with an uniform illumination angle. Therefore, it is a feasible technical solution to use light emitting diode as a light source by maximizing its advantages and minimizing its disadvantages.
As disclosed in R.O.C. Pat. No. M343772, a wide-angle illumination is provided for overcoming the drawback of the small illumination angle of the light emitting diode and providing a light emitting diode illuminator having the advantages of maximizing the life expectancy and reducing the power consumption of the light emitting diode. In FIG. 1, the light emitting diode illuminator 10 comprises a plurality of lamp housings 111 disposed on a lamp holder 11, an illumination end formed as an open end at the bottom of each housing, and at least two opposite hollow sidewalls disposed on the housing 111.
In addition, a light source module 12 for producing a light source includes a plurality of light emitting diodes 122 installed on a circuit board 121 and installed onto the lamp holder 11 with a corresponding outward inclination, and the light emitting diodes 122 on the circuit board 121 are exposed from opposite hollow sidewalls in each housing 111, and opposite to the illumination end of the housing 111 by an inclination. With the foregoing structure, the light emitting diodes 122 of each housing 111 installed in the lamp holder 11 provide illumination with a corresponding opposite outward angle and extend the illumination angle of an illumination end of each housing to increase the overall illumination angle of an illuminator.
In FIG. 2, the aforementioned conventional light emitting diode illuminator 10 is generally used for outdoor road illumination, but the illumination end of each housing 111 of the conventional light emitting diode illuminator 10 is aligned precisely with the bottom of the lamp holder 11, and thus the light projection range of the illuminator is limited to an area (as shown in FIG. 2) precisely opposite to the bottom of the lamp holder 11 only. When such light emitting diode illuminator is used as a road illuminator, it is necessary to install the LED illuminator with an inclination, so that the light source can project light towards the road, and such way of installing light emitting diode illuminators is applicable for roads in Taiwan, but not suitable for other foreign countries, since those installations are generally horizontal installations. As a result, the actual light projection on the road is very limited, and the conventional LED illuminator requires further improvements.